U.S. patent application number 16/652983 was filed with the patent office on 2020-07-30 for insulation piercing cable connection system.
This patent application is currently assigned to Nederlandse Organisatie voor toegepast-natuurwetenschappelijk onderzoek TNO. The applicant listed for this patent is Nederlandse Organisatie voor toegepast-natuurwetenschappelijk onderzoek TNO. Invention is credited to Hendrik Cornelis HAKKESTEEGT, Stan Anton Willem KLERKS.
Application Number | 20200244218 16/652983 |
Document ID | 20200244218 / US20200244218 |
Family ID | 1000004766652 |
Filed Date | 2020-07-30 |
Patent Application | download [pdf] |
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United States Patent
Application |
20200244218 |
Kind Code |
A1 |
HAKKESTEEGT; Hendrik Cornelis ;
et al. |
July 30, 2020 |
INSULATION PIERCING CABLE CONNECTION SYSTEM
Abstract
The invention is directed to an insulation piercing cable
connection system, to an insulation piercing cable and an
insulation piercing connector for use in said insulation piercing
cable connection system, and to a photovoltaic system.
Inventors: |
HAKKESTEEGT; Hendrik Cornelis;
(Abbenes, NL) ; KLERKS; Stan Anton Willem;
(Rotterdam, NL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Nederlandse Organisatie voor toegepast-natuurwetenschappelijk
onderzoek TNO |
's-Gravenhage |
|
NL |
|
|
Assignee: |
Nederlandse Organisatie voor
toegepast-natuurwetenschappelijk onderzoek TNO
's-Gravenhage
NL
|
Family ID: |
1000004766652 |
Appl. No.: |
16/652983 |
Filed: |
October 2, 2018 |
PCT Filed: |
October 2, 2018 |
PCT NO: |
PCT/NL2018/050654 |
371 Date: |
April 1, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H02S 40/34 20141201;
H02S 40/32 20141201; H01L 31/02008 20130101; H02S 40/36
20141201 |
International
Class: |
H02S 40/32 20060101
H02S040/32; H01L 31/02 20060101 H01L031/02; H02S 40/36 20060101
H02S040/36; H02S 40/34 20060101 H02S040/34 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 2, 2017 |
EP |
17194299.8 |
Claims
1. An insulation piercing cable connection system, comprising an
insulation piercing cable, and an insulation piercing cable
connector, wherein said insulation piercing cable comprises a flat
cable having a plurality of three or more conductors embedded in
insulation material, wherein a cross-section of the insulation
piercing cable has a perimeter with two orthogonal axes of
symmetry, wherein the conductors as arranged in said cross-section
has point symmetry, wherein said insulation piercing cable
connector comprises a cavity for receiving said insulation piercing
cable, wherein said cavity comprises a plurality of three or more
cable piercing conductors, wherein the plurality of cable piercing
conductors in the insulation piercing cable connector is equal to
the plurality of conductors in the insulation piercing cable, and
wherein said insulation piercing cable connector is compatible to
be electrically connected to said insulation piercing cable by
piercing the insulation of said insulation piercing cable with said
cable piercing conductors.
2. The insulation piercing cable connection system according to
claim 1, connected to a single power circuit, wherein at least two
outer cable piercing conductors in said insulation piercing cable
connector are connected to each other and to a first external
conductor, and one or more inner cable piercing conductors are
connected to each other and to a second external conductor.
3. The insulation piercing cable connection system according to
claim 1, connected to two separate power circuits, wherein at least
two outer cable piercing conductors in said insulation piercing
cable connector are connected to two distinct inner cable piercing
conductors via two separate external conductors, and wherein
conductors of the insulation piercing cable connector are connected
to each other and the power circuits.
4. The insulation piercing cable connection system according to
claim 1, wherein the perimeter of said cross-section has a
rectangular shape.
5. The insulation piercing cable connection system according to
claim 4, wherein said rectangular shape is rounded.
6. The insulation piercing cable connection system according to
claim 1, wherein said insulation piercing cable comprises four or
more conductors in a plane.
7. The insulation piercing cable connection system according to
claim 1, wherein the plurality of conductors in the insulation
piercing cable is even.
8. The insulation piercing cable connection system according to
claim 1, wherein said insulation piercing cable comprises a
polarity indication for each of said three or more conductors
comprised in said cable, and wherein the indication is such that in
a cross-section of said cable, an arrangement of polarities as
indicated by the polarity indication has point symmetry.
9. The insulation piercing cable connection system according to
claim 3, wherein said insulation piercing cable comprises four
conductors and wherein the four conductors are used for two
separate power circuits.
10. The insulation piercing cable connection system according to
claim 1, in combination with a converter with a DC-output.
11. The insulation piercing cable connection system according to
claim 1, in combination with a converter with an AC-output.
12. The insulation piercing cable connection system according to
claim 3, combined with power line communication, wherein one or
more power line communication modules are connected between the
said two separate power circuits of the insulation piercing
cable.
13. The insulation piercing cable for use in the insulation
piercing cable connection system according to claim 1, said
insulation piercing cable comprising a flat cable having a
plurality of three or more conductors embedded in insulation
material, wherein a cross-section of the insulation piercing cable
has a perimeter with two orthogonal axes of symmetry, and wherein
the conductors as arranged in said cross-section has point
symmetry.
14. The insulation piercing cable connector for use in the
insulation piercing cable connection system according to claim 1,
said insulation piercing cable connector comprising a cavity for
receiving said insulation piercing cable, wherein said cavity
comprises a plurality of three or more cable piercing conductors,
wherein the plurality of cable piercing conductors in the
insulation piercing cable connector is equal to the plurality of
conductors in the insulation piercing cable, and wherein said
insulation piercing cable connector is compatible to be
electrically connected to said insulation piercing cable by
piercing the insulation of said insulation piercing cable with said
cable piercing conductors.
15. A photovoltaic system, comprising one or more photovoltaic
modules connected to one or more converters via one or more
insulation piercing cables connection systems according to claim
1.
16. A photovoltaic system, comprising one or more photovoltaic
modules connected to one or more inverters via one or more
insulation piercing cable connection systems according to claim
1.
17. The photovoltaic system according to claim 16, wherein the one
or more inverters are further connected to one or more converters
via one or more insulation piercing cable connection systems.
18. A photovoltaic system, comprising one or more photovoltaic
modules connected to one or more converters via one or more
insulation piercing cables according to claim 13.
19. A photovoltaic system, comprising one or more photovoltaic
modules connected to one or more converters via one or more
insulation piercing cable connectors according to claim 14.
20. A photovoltaic system, comprising one or more photovoltaic
modules connected to one or more inverters via one or more
insulation piercing cables according to claim 13.
21. A photovoltaic system, comprising one or more photovoltaic
modules connected to one or more inverters via one or more
insulation piercing cable connectors according to claim 14.
Description
[0001] The invention is directed to an insulation piercing cable
connection system, to an insulation piercing cable and an
insulation piercing connector for use in said insulation piercing
cable connection system, and to a photovoltaic system.
[0002] Photovoltaic devices are well known in the art. Such devices
absorb sunlight and convert it directly into useable electrical
energy. A typical photovoltaic cell is a solid-state device in
which a junction is formed between adjacent layers of semiconductor
materials doped with specific atoms. When light energy or photons
strike the semiconductor, electrons are dislodged from the valence
band. These electrons, collected by the electric field at the
junction, create a voltage that can be put at work in an external
circuit. The basic principles that underlie this effect are
well-known and understood to those in the art.
[0003] While solar power generation is a clean method of generating
energy, there remains a lack of a cohesive integrated
infrastructure that uses solar energy as a power source. In
addition, some customers find the appearance of solar panels on
roofs unappealing and unattractive.
[0004] It would be desirable if solar power generation could be
integrated in trafficable surfaces such as roads, parking lots,
driveways, sidewalks and the like.
[0005] In recent years, photovoltaic trafficable surfaces have
emerged as a solution to increase the amount of energy harvested
from the sun. A photovoltaic trafficable surface known as
SolaRoad.RTM. is located in the town of Krommenie in the
Netherlands. This photovoltaic trafficable surface comprises a top
layer of tempered glass of about 1 cm thick with underneath
crystalline silicon solar cells. The SolaRoad.RTM. system is
prefabricated as a whole as 2.5 by 3.5 metre concrete modules
comprising the polycrystalline silicon solar cells. These modules
have to be transported to the road site and placed as such on the
desired location. It is not possible to replace only part of a
concrete module upon failure. This rather inflexible construction
method as well as inefficient maintenance requirement results in
high costs per covered surface area and produced energy unit.
[0006] The optimal electric architecture for large scale solar
power (photovoltaic) system which is subjected to irregular
shadowing, such as when integrated in a road surface, makes use of
local DC/DC (direct current/direct current) converters with
integrated Maximum Power Point Tracking (MPPT). These local
converters need to be connected to a DC-bus-cable to transport the
power to a central location. Cost reduction can be obtained when
this cabling system can be optimised both in terms of material cost
and labour.
[0007] The Dutch company NKF manufactured for a short period of
time (around the year 2002) the OK5 micro inverter which did not
use connectors for the connection of these micro inverters to the
bus-cable (also referred to as trunk cable). For the bus cable a
two conductor insulation piercing cable was used which was
originally designed for outside lighting applications. This
commonly available cable, with a symmetric rectangular
cross-section could only be used because the micro inverter
produces an alternating output voltage (AC, alternating current)
which means that there is no strict rule that contact number one of
the micro inverter has to be connected to conductor number one of
the cable. It is allowed to twist the cable and swap the
conductors, unlike cables that are used for direct current.
[0008] The OK5 micro inverter makes use of "standard" Power Line
Communication (PLC) over the two conductors of the cable which
requires relatively expensive electronic components which in
addition reduce the energy efficiency of the system due to
additional dissipation losses.
[0009] The German company Wieland Electric GmbH manufactures
insulation piercing flat cable connection systems for direct
current applications called Podis.TM. and Genesis.TM. which prevent
incorrect connection with the cable conductors by using a flat
cable wherein one lateral edge of a longitudinal cross-section of
the cable has a different shape than the opposing lateral edge of
the cross-section.
[0010] US-A-2011/0 036 386 discloses a fully integrated and
self-contained alternating current photovoltaic solar panel device,
which features an integral micro-inverter having a compression
connector fitting for electrically connecting the utility grid. An
insulating piercing connection is used to connect the alternating
current output of a micro inverter onto a three wire bus-cable.
Incorrect connection of the cable is prevented by using a cable
wherein one lateral edge of a longitudinal cross-section of the
cable has a flat shape, while the opposing lateral edge of the
cross-section has a rounded shape.
[0011] The insulation piercing flat cable connection systems
described in US-A-2011/0 036 386 and those manufactured by the
German manufacturer Wieland Electric GmbH prevent that the cable
can be connected `upside down`. This way it should be guaranteed
that conductor number one in the cable will be connected to
connection number one in the connected device. Preventing that
connections can be swapped is necessary for connecting to a direct
current (DC) bus. The systems used by Wieland Electric GmbH makes
use of a flat cable wherein the opposing lateral edges have
different shapes. The special shape of the cross-section should
make it impossible to insert the cable the wrong way around. The
drawback of this is that an additional twist of the cable, for
instance to reduce the stress on the connection, is not allowed.
The special shape with the non-rectangular cross-section is also
more expensive to manufacture.
[0012] US-B-9 225 286 discloses an insulation piercing cable
connection system, comprising an insulation piercing cable, or
output cable, and an insulation piercing cable connector, or trunk
cable. The insulation piercing cable connection system disclosed
herein requires a pre-set connector orientation. There is only one
possible way of connecting the system. Improper assembly is
prevented by the presence of a keying feature at the bottom of a
snap-in cover and a corresponding indent in the trunk cable. It is
clear from FIG. 5 of US-B-9 225 286 that improper assembly results
in an embodiment that does not work properly.
[0013] DE-B-10 2014 115 601 discloses a junction box wherein the
individual inverters at each photovoltaic modules are jointly
connected.
[0014] There remains a need in the art for improved insulation
piercing cable connection systems. In particular, it is desirable
when an insulation piercing cable connection system can be used in
combination with direct current.
[0015] Objective of the invention is to address this need in the
art and/or to overcome one or more drawbacks of prior art
insulation piercing cable connection systems.
[0016] The inventors found that this objective can be met, at least
in part, by providing a specially designed insulation piercing
cable connection system.
[0017] Accordingly, in a first aspect the invention is directed to
an insulation piercing cable connection system, comprising an
insulation piercing cable, and an insulation piercing cable
connector, wherein said insulation piercing cable comprises a flat
cable having three or more conductors embedded in insulation
material, wherein a cross-section of the insulation piercing cable
has a perimeter with two orthogonal axes of symmetry, and wherein
the arrangement of conductors in said cross-section has point
symmetry, and wherein said insulation piercing cable connector
comprises a cavity for receiving said insulation piercing cable,
wherein said cavity comprises three or more cable piercing
conductors, wherein the amount of cable piercing conductors in the
insulation piercing cable connector is the same as the amount of
conductors in the insulation piercing cable, and wherein said
insulation piercing cable connector is compatible to be
electrically connected to said insulation piercing cable by
piercing the insulation of said insulation piercing cable with said
cable piercing conductors.
[0018] By using a flat cable with three or more conductors that has
a combination of a cross-section (perpendicular to the longitudinal
axis of the cable) having a perimeter with two orthogonal axes of
symmetry and a point symmetrical arrangement of conductors in said
cross-section it is possible to use a cable which may also be
connected `upside down` and is relatively easy to manufacture. The
insulation piercing cable connection system of the invention can be
used either in combination with direct current, or with alternating
current.
[0019] The term "flat cable" as used herein is meant to refer to
its commonly known meaning, i.e. a cable having a longitudinal
cross-section of which the width is larger than the height. Hence,
the aspect ratio (width divided by height) of the longitudinal
cross-section of a flat cable is larger than 1.
[0020] The term "insulation piercing cable" as used herein is meant
to refer to a cable that is suitable for insulation piercing
contacts, viz. contacts that are realised by piercing the
insulation of the cable and thereby electrically contacting the
conductors comprised therein to external conductors.
[0021] The insulation piercing cable connection system of the
invention may be connected to a single power circuit, such that at
least the two outer cable piercing conductors in the insulation
piercing cable connector are connected to each other and to a first
external conductor, and an inner cable piercing conductors is
connected to a second external conductor. It is also possible to
have more than one inner cable piercing conductors, which may then
be connected to each other and to the second external
conductor.
[0022] The insulation piercing cable connection system of the
invention may also be connected to two separate power circuits,
such that at least the two outer cable piercing conductors in said
insulation piercing cable connector are connected to two distinct
inner cable piercing conductors via two separate external
conductors, and wherein conductors of the insulation piercing cable
connector are connected to each other and the power circuits.
[0023] In accordance with the invention, preferably direct current
is used. This is unlike the OK5 micro inverter manufactured by NKF
which makes use of alternating current (AC). A direct current bus
voltage is advantageous, because an alternating current requires
more complex converters electronics with an additional AC-output
stage which requires more electronic components and therefore will
be bigger, will have a higher manufacturing cost and lower
reliability.
[0024] Additionally, the OK5 micro inverter manufactured by NKF
makes use of Power Line Communication (PLC) over the two conductors
of the flat cable which lead to reduced energy conversion
efficiency due to losses in the PLC coupling components and the
dissipation in the PLC circuit. The invention, on the other hand,
uses additional conductors in the cable where, in the case of four
conductors or more, PLC can be used without the energy consuming,
expensive components that are required in the case of a
conventional two conductor PLC.
[0025] In a solar power photovoltaic system, with local converters,
the output of the local converters are typically connected by means
of a bus cable (also called trunk cable). In such as system, the
bus cable ideally operates at direct current (DC) instead of
alternating current (AC). The advantages of DC over AC in this case
is that the electronic circuitry in the converters can be kept
simpler because an AC-output stage can be omitted. This means that
less electronic components are necessary which reduces costs, size,
dissipation, and increases the reliability of the converter. The
use of DC instead of AC for the bus cable has additional advantages
such as higher power transfer capability because the cable can be
operated constantly at its maximum voltage, where in case of a sine
wave AC voltage the effective (RMS) voltage is a factor 0.71 below
the peak voltage.
[0026] Connection to a DC bus means that the conductors may not be
swapped in contrast with connection to an AC bus where swapping of
the conductors can be allowed. To make sure that a flat insulation
piercing cable system cannot be connected the wrong way around,
conventionally special shapes of the cross-section of such cables
have been used, which special shapes only allow to electrically
connect the cable in a single manner. Such a special cross-section
is relatively expensive to manufacture and it prevents the
possibility to twist the cable by 180 degrees at will, for instance
to reduce the stress on the connection. The insulation piercing
cable used in the insulation piercing cable connection system of
the invention has three or more conductors and a cross-section
having a perimeter with two orthogonal axes of symmetry and a point
symmetrical arrangement of conductors in said cross-section. This
allows for the cable to be installed in both ways (so also upside
down), and in addition guarantees that the plus and minus
conductors of the DC bus system are connected the right way. The
insensitivity to the installation direction of the cable makes that
the cable is attractive for manufacturing and allows twisting of
the cable to prevent stress on the connections.
[0027] Communication with the converters used in a solar power (PV)
system can be performed by means of wireless Radio Frequency (RF)
communication. However, the specific characteristics of a solar
power system integrated in a road surface hinder the operation of
an RF communication link. Especially, the location of antennas
close to the ground that can be wet results in undesirably high
attenuation of the RF-link. The alternative for RF communication is
power line communication (PLC) which is sometimes used for solar
power converters. The drawback of conventional PLC is that it
requires additional relatively expensive and energy consuming
electronic components. The invention also provides for the
possibility of using PLC but not in the traditional way over the
power lines which means that considerably less energy is consumed
and also less expensive components are necessary.
[0028] In a large scale solar power photovoltaic (PV) system, the
individual solar panels can be connected in series. This string of
in series connected panels is then connected to a grid connected
central inverter which transforms the DC current from the PV panels
to the AC current of the grid. This setup works well and is
efficient when there is not too much hinder from shadows both from
objects as well as from clouds. However, when shadows occur
frequently performance degradation will result. This performance
degradation can be limited when electronic converters are added at
panel level which include Maximum Power Point Tracking (MPPT).
Although it is possible to connect the output of these local
converters in series, the preferred option is parallel connection
to a `bus` in combination with a relatively high output voltage. A
further distinction can be made between direct current (DC) and
alternating current (AC). AC may have the benefit that the output
of the micro inverters can be connected directly to the grid, but
for a large scale solar power system, in particular when combined
with a road surface, the preference is to use a DC bus voltage.
[0029] The outputs of all the individual local converters have to
be connected to the DC-bus. The stretched or lint shape of a solar
power system, especially when integrated in a road surface, makes
that the preferred interconnection method is the use of a bus-cable
or trunk cable onto which all local converters are connected. This
bus-cable with all of its connectors forms a considerable part of
costs of the electric system resulting both from the material cost
as well as from the labour related to preparation and installation.
A considerable cost reduction can be obtained when the conventional
connectors can be omitted. A known solution is the use of an
insulation piercing connection system (also called insulation
displacement connection), where an insulation piercing cable is
pressed into a cavity of a insulation piercing cable connector
which has a shape that corresponds with the shape of the
cross-section of the cable. The insulation piercing connector
further includes cable piercing conductors that pierce through the
insulation of the cable and make contact with the conductors of the
cable. A well-known implementation of this connection system is a
two conductor cable which has a symmetrical rectangular shape, and
which is used for outdoor lighting. Due to its symmetrical shape
the cable can be connected in two ways which means that it is not
known upfront which contact of the insulation piercing connector is
connected to which conductor in the cable (FIG. 1). This does not
have to be a problem in case of an AC application and can, for
instance, be used to connect micro inverters with their AC
outputs.
[0030] FIG. 1 shows such a conventional insulation piercing
connection system with conductors 1 and 2, and a symmetric
rectangular cross-section of cable 5 that can be used for AC
application. The cable can be connected to insulation piercing
cable connector 6 that has a shape that is complementary to the
shape of cable 5. Connector 6 further includes cable piercing
conductors 7 and 8 that pierce through the insulation cable 5 and
make contact with conductors 1 and 2 of cable 5. In FIG. 1,
polarity that can be applied is indicated by A and B. In case of an
AC application, it is irrelevant whether the cable conductor with
polarity A is connected to the cable piercing conductor with
polarity A or B, and whether the cable conductor with polarity B is
connected to the cable piercing conductor with polarity A or B.
However, in case of a DC-bus voltage it has to be guaranteed that
the plus and minus connections of the local converter are connected
with the plus and minus of the DC-bus cable, respectively. With
reference to FIG. 1, this means that the conductor with polarity A
should be connected to the cable piercing conductor with polarity A
and that the conductor with polarity B should be connected to the
cable piercing conductor with polarity B. Incorrect electrical
connection of the cable to the connector can be avoided by using a
cable wherein the opposing lateral edges of a longitudinal
cross-section have a different shape, such that the cable can only
be connected to the connector in one way (not shown). Such cable
will then not have a cross-section having a perimeter with two
orthogonal axes of symmetry.
[0031] Instead, the insulation piercing cable connection system of
the invention utilises an insulation piercing cable comprising a
flat cable having three or more conductors embedded in insulation
material, wherein a cross-section of the insulation piercing cable
has a perimeter with two orthogonal axes of symmetry, and wherein
the arrangement of conductors in said cross-section has point
symmetry. Such a cable with preferably a rectangular (optionally
rounded), cross-section, is easier to manufacture.
[0032] The insulation piercing cable connection system of the
invention further utilises an insulation piercing cable connector
in combination with the insulation piercing cable, comprising a
cavity for receiving said insulation piercing cable, wherein said
cavity comprises three or more cable piercing conductors, wherein
the amount of cable piercing conductors in the insulation piercing
cable connector is the same as the amount of conductors in the
insulation piercing cable, and wherein the insulation piercing
cable connector is compatible to be electrically connected to said
insulation piercing cable by piercing the insulation of said
insulation piercing cable with said cable piercing conductors. By
piercing the insulation of the insulation piercing cable with the
cable piercing conductors, the conductors in the insulation
piercing cable connected are electrically connected (viz. are in
electrical contact) to the respective conductors in the insulation
piercing cable.
[0033] A schematic example of an embodiment of the invention is
shown in FIG. 2. This figure shows an insulation piercing cable 5
with three conductors (1, 2 and 3). Cable 5 is to be connected to
insulation piercing cable connector 6, which has three cable
piercing conductors (7, 8 and 9). The two outer conductors (1 and
3) in insulation piercing cable 5 are used for the same polarity in
FIG. 2 indicated with B. When insulation piercing cable 5 is
connected to insulation piercing cable connector 6, conductors 1
and 3 will be connected to cable piercing conductors 7 and 9, which
are used for the same polarity B. It does not matter in FIG. 2
whether conductor 1 will be connected to cable piercing conductor 7
and conductor 3 to cable piercing conductor 9, or whether conductor
1 will be connected to cable piercing conductor 9 and conductor 3
to cable piercing conductor 7. Conductor 2 will always be connected
to cable piercing conductor 8. Hence, this configuration guarantees
that contact-B of the insulation piercing cable connector is
connected to contact-B on the insulation piercing cable side, and
that contact-A of the insulation piercing cable connector is
connected to contact-A on the insulation piercing cable side. It is
not important whether the cable is inserted `upside down` (herein
also referred to as `reversed`). The insulation piercing cable
connection system shown in FIG. 2 can be used both for AC as well
as DC applications. Inserting the cable upside down may be
beneficial in certain cases to reduce the strain on the connections
resulting from a twisted cable.
[0034] Preferably, the conductors in the flat cable may all be
arranged in one plane. In a preferred embodiment, a cross-section
of the insulation piercing cable has two orthogonal axes of
symmetry. The centre of point symmetry is shown in FIG. 2 by an
asterisk. Two axes of symmetry are shown for the embodiment in FIG.
2 by dotted lines.
[0035] It is preferred for the insulation piercing cable to
comprise four or more conductors in a plane. Such a configuration
provides the possibility for Power Line Communication (PLC) without
efficiency reduction due to dissipation in the electronic
components which is the case for conventional PLC, as will be
explained herein below.
[0036] The insulation piercing cable connection system may be
combined with a converter either with a DC-output or with an
AC-output, preferably a converter with a DC-output.
[0037] Preferably, the amount of conductors in the insulation
piercing cable is even. More preferably, the amount of the
conductors used for different polarity in the insulation piercing
cable is the same. Although it is possible to employ an uneven
amount of conductors, this will automatically mean that there are
more conductors of one polarity than there are conductors of the
other polarity in the insulation piercing cable. In such an
embodiment, the conductor cross-section (or conductor diameter) of
the conductors with the polarity which is in the majority may
optionally be reduced to balance the loading of the conductors for
optimal use of the conductor material, although this will lead to
higher manufacturing costs. Preferably, the conductor cross-section
(or conductor diameter) of each conductor in the insulation
piercing cable is the same.
[0038] The insulation piercing cable connector is compatible to be
electrically connected with the insulation piercing cable of the
invention. This means that the insulation piercing cable can be
electrically connected to the connector such that the cable
piercing conductors of the insulation piercing cable connector
pierce through the insulation of the insulation piercing cable and
each cable piercing conductor of the insulation piercing cable
connector connects electrically to a different conductor in the
insulation piercing cable.
[0039] Correct connection of contacts (viz. polarities) A and B can
be guaranteed with any number of conductors with a minimum of
three. In case of the three conductor configuration presented in
FIG. 2, the current through contact B is distributed over two
conductors in the cable, compared to only one conductor in the
cable for contact A. This means that the conductor cross-section of
the outer conductors used for contact B can be reduced to balance
the loading of the conductors if necessary. This may yield a cost
benefit. Another approach is to use a cable with an additional
conductor. In FIG. 3, insulation piercing cable 5 has four
conductors (1, 2, 3, and 4). Insulation piercing cable 5 is to be
connected to insulation piercing cable connector 6, which has four
cable piercing conductors (7, 8, 9, and 10). The centre of point
symmetry is shown in FIG. 3 by an asterisk, and two axes of
symmetry are shown with dotted lines. In this configuration, each
contact A and B uses two conductors in parallel. The two outer
conductors (1 and 4) in insulation piercing cable 5 are used for
the same polarity, in FIG. 3 indicated with B. When insulation
piercing cable 5 is connected to insulation piercing cable
connector 6, conductors 1 and 4 will always be connected to cable
piercing conductors 7 and 9, which are also used for polarity B.
Conductors 2 and 3 will always be connected to cable piercing
conductors 8 and 10. It does not matter in FIG. 3 whether conductor
1 will be connected to cable piercing conductor 7, conductor 2 to
cable piercing conductor 8, conductor 3 to cable piercing conductor
10 and conductor 4 to cable piercing conductor 9, or whether
conductor 1 will be connected to cable piercing conductor 9,
conductor 2 to cable piercing conductor 10, conductor 3 to cable
piercing conductor 8 and conductor 4 to cable piercing conductor 7.
An additional benefit resulting from this approach is increased
reliability due to the introduction of redundancy. If one contact
or conductor breaks, the system will keep on operating due to the
parallel connection. The insulation piercing cable connection
system shown in FIG. 3 can be used both for AC as well as DC
applications.
[0040] When four conductors are available in the cable they can be
interconnected to support only the two contacts A and B as
illustrated in FIG. 3. It is, however, also possible to make a
separation between two power circuits as illustrated in FIG. 4. In
FIG. 4, insulation piercing cable 5 has four conductors (1, 2, 3,
and 4). Cable 5 is to be connected to insulation piercing cable
connector 6, which has four cable piercing conductors (7, 8, 9, and
10). The centre of point symmetry is shown in FIG. 4 by an
asterisk, and two axes of symmetry are shown with dotted lines. The
two outer conductors (1 and 4) in insulation piercing cable 5 are
used for the same polarity. When insulation piercing cable 5 is
connected to insulation piercing cable connector 6, conductors 1
and 4 will always be connected to cable piercing conductors 7 and
9, which are used for the same polarity (positive polarity in FIG.
4), but for different power circuits. Conductors 2 and 3 will
always be connected to cable piercing conductors 8 and 10, which
are used for the polarity opposite to that of the two outer cable
piercing conductors 7 and 9 (negative polarity in FIG. 4), but for
different power circuits. It does not matter in FIG. 4 whether
conductor 1 will be connected to cable piercing conductor 7,
conductor 2 to cable piercing conductor 8, conductor 3 to cable
piercing conductor 10 and conductor 4 to cable piercing conductor
9, or whether conductor 1 will be connected to cable piercing
conductor 9, conductor 2 to cable piercing conductor 10, conductor
3 to cable piercing conductor 8 and conductor 4 to cable piercing
conductor 7. This configuration thus still allows the swapping of
the cable (inserting upside down), when the polarity of the
contacts is oriented to support this and the voltage of the two
power circuits is compatible. Also this insulation piercing cable
connection system shown in FIG. 4 can be used both for AC as well
as DC applications.
[0041] The configuration with the two separate power circuits, as
presented in FIG. 4, opens the possibility to combine the power
transportation function of the bus-cable with a communication
function. Communication between the local converters and a central
unit can be attractive for multiple reasons. Messages from the
local converters can contain information about the performance and
error states. Messages in opposite direction from a central
location to the local converters can be used to reduce the power
output when requested or demanded by the grid operator to maintain
the power quality on the grid. The local converters can also be
instructed to shut down completely for safety reasons, for instance
in case of an accident or a fire. When the bus cable is used for AC
power transfer, the converters can also be instructed by the grid
operator to generate reactive power to maintain the power quality
on the grid.
[0042] Hence, in a special embodiment the insulation piercing cable
comprises four conductors, wherein the four conductors are used for
two separate power circuits.
[0043] Communication between a central unit and the local
converters can be implemented by means of a wireless radio
frequency (RF) link. However, the specific characteristics of a
solar power system integrated in a road surface hinder the
operation of an RF communication link. Especially the location of
antennas close to the ground that can be wet result in high
attenuation of the RF-link. The alternative for RF communication is
power line communication (PLC) which is sometimes used for solar
power converters. However, the drawback of conventional PLC is that
it requires additional relative expensive and energy consuming
electronic components. The multi conductor configuration presented
in FIG. 4, however, provides the possibility to use PLC at a
considerably lower power level thus consuming less energy which
means less impact on the efficiency of the total system and less
expensive electronic components necessary to implement PLC compared
to a conventional PLC implementation.
[0044] FIG. 5 shows an electronic diagram wherein two local
converters are connected in opposite ways to a four-conductor
bus-cable. As illustrated in the electronic diagram shown in FIG.
5, the PLC communication modules are not connected between the
power lines of a power circuit which is the conventional PLC
implementation, but the communication module is now connected
between the two separate power circuits. Hence, the insulation
piercing cable connection system with four conductors that are used
for two separate power circuits can be combined with power line
communication, such that power line communication modules are
connected between the two separate power circuits of the insulation
piercing cable. When the communication module is connected in the
traditional way, the communication module is loaded with the low
impedance of the power converters connected to the same conductors.
However, when the communication module is connected between the two
power circuits, the loading is much lower which means that less
power has to be put in the transmitter circuits to end up at a high
enough signal level at the receivers for reliable communication. It
is no problem that the two separate power circuits are
interconnected behind the central power converters (inverters)
because the galvanic isolation in these converters maintain the
separation between the power circuits preventing `shorting` of the
communication modules. Parallel connection of the output of
inverters is common practice and happens for instance when using
multiple micro inverters. The multi conductor configuration is
introduced to allow a reversed connection of the convertors as
described above resulting from a `upside down` connection of the
insulation piercing cable. The resulting reversed connection of the
communication modules as visible in FIG. 5 does not hinder the
communication because the communication modules make use of an AC
signal (carrier) that is coupled by means of capacitors.
[0045] In a further aspect, the invention is directed to a
photovoltaic system, comprising one or more photovoltaic modules
connected to one or more converters via one or more insulation
piercing cable connection systems according to the invention.
[0046] The photovoltaic system is preferably integrated in a
roadway surface to generate solar power.
[0047] In yet a further aspect, the invention is directed to a
photovoltaic system, comprising one or more photovoltaic modules
connected to one or more inventers via one or more insulation
piercing cable connection systems according to the invention. When
photovoltaic modules are integrated in applications such as in a
roadway, the photovoltaic modules are individually connected to an
inverter, amongst others for safety reasons. The circuit between
the photovoltaic module and the inverters is a safety extra low
voltage (SELV) circuit. This allows using an insulation piercing
cable connection system according to the invention, instead of the
conventional connection technology found in photovoltaic modules,
such as MC4 (Multi-Contact 4 mm diameter).
[0048] Conventionally, the wires of a photovoltaic module are fixed
to the junction box on the back of the module and have connectors
to connect these to an inverter, or to the next modules, if placed
in series. These connection systems are also developed for 1000 to
1500 V direct current (so not SELV) ratings.
[0049] The integration of photovoltaic modules in roadways leads to
other connection demands as well. Ideally, a single photovoltaic
module can be replaced, such as described in co-pending European
patent application number 17194363.2. This is difficult if the
wires cannot be disconnected at the junction box. On the other
hand, the connection should also be disconnectable at the inverter,
for installation ease. The use of an insulation piercing cable
connection system as described herein, is very useful for such
applications as well. Possible future monitoring devices may be
installed, i.e. on a chip basis, in individual photovoltaic
modules. This information can then also be transferred via the
power line communication solution described earlier.
[0050] This connection concept was never an option for conventional
photovoltaic modules because of the high voltage and current
applied in a typical photovoltaic system. However, when integrated
in roadway assemblies, it is possible to work with SELV levels on
the module side, and the interconnection requirements are somewhat
different. This allows to connect the photovoltaic modules to the
inventers with an insulation piercing cable connection system of
the invention.
[0051] This is schematically shown in FIG. 6. This figure shows a
photovoltaic module 11 that has a junction box 12 with an
insulation piercing cable connector. Symmetrical insulation
piercing cable 13 electrically connects photovoltaic module 11 to
micro-inverter 14. Micro-inverter 14 has insulation piercing cable
connectors such that it can be electrically connected to insulation
piercing cable 13 and to bus-cable 15, which serves to transport
the power to a central location. Bus-cable (or trunk cable) 15 is
also an insulation piercing cable as described herein.
[0052] Accordingly, the photovoltaic system preferably comprises
one or more photovoltaic modules connected to one or more inventers
via one or more first insulation piercing cable connection systems
according to the invention, as well as one or more second
insulation piercing cable connection systems according to the
invention that connect the one or more inverters to one or more
converters.
[0053] The invention has been described by reference to various
embodiments, compositions and methods. The skilled person
understands that features of various embodiments, compositions and
methods can be combined with each other.
[0054] All references cited herein are hereby completely
incorporated by reference to the same extent as if each reference
were individually and specifically indicated to be incorporated by
reference and were set forth in its entirety herein.
[0055] The use of the terms "a" and "an" and "the" and similar
referents in the context of describing the invention (especially in
the context of the claims) are to be construed to cover both the
singular and the plural, unless otherwise indicated herein or
clearly contradicted by context. The terms "comprising", "having",
"including" and "containing" are to be construed as open-ended
terms (i.e., meaning "including, but not limited to") unless
otherwise noted. Recitation of ranges of values herein are merely
intended to serve as a shorthand method of referring individually
to each separate value falling within the range, unless otherwise
indicated herein, and each separate value is incorporated into the
specification as if it were individually recited herein. The use of
any and all examples, or exemplary language (e.g., "such as")
provided herein, is intended merely to better illuminate the
invention and does not pose a limitation on the scope of the
invention unless otherwise claimed. No language in the
specification should be construed as indicating any non-claimed
element as essential to the practice of the invention. For the
purpose of the description and of the appended claims, except where
otherwise indicated, all numbers expressing amounts, quantities,
percentages, and so forth, are to be understood as being modified
in all instances by the term "about". Also, all ranges include any
combination of the maximum and minimum points disclosed and include
any intermediate ranges therein, which may or may not be
specifically enumerated herein.
[0056] Preferred embodiments of this invention are described
herein. Variation of those preferred embodiments may become
apparent to those of ordinary skill in the art upon reading the
foregoing description. The inventors expect skilled artisans to
employ such variations as appropriate, and the inventors intend for
the invention to be practiced otherwise than as specifically
described herein. Accordingly, this invention includes all
modifications and equivalents of the subject-matter recited in the
claims appended hereto as permitted by applicable law. Moreover,
any combination of the above-described elements in all possible
variations thereof is encompassed by the invention unless otherwise
indicated herein or otherwise clearly contradicted by context. The
claims are to be construed to include alternative embodiments to
the extent permitted by the prior art.
[0057] For the purpose of clarity and a concise description
features are described herein as part of the same or separate
embodiments, however, it will be appreciated that the scope of the
invention may include embodiments having combinations of all or
some of the features described.
* * * * *